The Data Coordinating Center will support the activities of the Prevention of Adult Caries Study (PACS). PACS primary aims are 1) to test the hypothesis that chlorhexidine (10% w/v) dental coating, compared to a placebo coating, reduces adult caries increment in at-risk adults, and 2) to evaluate the cost and cost- effectiveness of using the chlorhexidine (10% w/v) coating in four dental care delivery systems. The Data Coordinating Center will provide administrative, logistical, and biostatistical support for the development, implementation, and successful completion of the PACS protocol. To accomplish this objective, the DCC will: 1) develop a secure study-specific Web portal to serve as a primary resource for study-wide communication, data entry, documentation, and monitoring;2) arrange for and conduct ongoing training and certification of study staff with respect to data collection, data entry, and trial monitoring;3) monitor recruitment and timeliness of data acquisition and data entry at the clinics and carry out quality assurance (QA) procedures on all study data;4) establish a protocol for generating and allocating randomization assignments and appropriate labeling of study treatments;5) track the collection, transfer, and laboratory analysis of microbiology specimens and conduct statistical analysis of the results data;6) conduct yearly site visits to monitor clinic and laboratory compliance with Good Clinical Practice guidelines;7) coordinate overall study activities, including scheduling meetings and conference calls, recording and distributing minutes, and preparing study materials (e.g., patient eligibility quick reference cards, patient information brochures);8) provide logistical support to the Data and Safety Monitoring Board, including scheduling meetings and conference calls, recording and distributing minutes, and reimbursing for expenses and honoraria;9) actively participate at the national level on trial-wide committees;10) provide statistical consultation and analytic support to study investigators, including formulating and executing a comprehensive plan for analysis of study data, preparing supporting documentation for an FDA new drug application, and supporting preparation of study-approved papers;11) develop and maintain a system to identify dental care utilization and valuations, and provide support to study investigators at each clinical center to establish utilization and cost data collection and quality control procedures;12) develop systems that facilitate the timely analysis of study data and the preparation and production of manuscripts;13) prepare and oversee distribution of the final ("locked") study data;and 14) prepare a public Web page to provide information (in lay terms) regarding PACS and to post synopses of study findings.